Process for producing composite pigments.



UNITED STATES PATENT OFFICE.

ANSIL MOFFATT, OF INDIANAPOLIS, INDIANA, ASSIGNOR TO ALBA MANUFACTURING COMPANY, OF INDIANAPOLIS, INDIANA, A CORPORATION OF INDIANA.

PROCESS FOR PRODUCING COMPOSITE PIG-MENTS.

Specification of Letters Patent.

Patented Feb. 9, 1909.

Application filed January 7, mos. Serial No. 409,6"15.

Producing Composite Pigments, of which the follovr ing is a specification.

My invention consists in a process for producing a composite white pi ment consisting of zinc oxid and barium sulfate in a state of coiprecipitation.

t is well known that composite pigments or rather pigments of a composite nature, are inferior in use for painting to pigments of simple nature, in body and covering power, unless the components of the composite pigment are produced simultaneously, either by co-precipitation or by co-reaction, in which case they invariably surpass those of simple nature as well as their lndividu'al constituents in the desired qualities. For example, the pigment'called in trade lithopone owes its value to the fact that its components are co-precipitated. It is made by mix-in so-- lut1ons of barium sulfid and zinc srdfate whereby the bases exchange acids and the result is a co-precipitated pigment of barium sulfate and zinc sulfid in molecular proportions, the resulting pigment surpassing either of its constituents in paintin or pigment value. Also, the pigment wefi known as white lead is a composite pigment of lead carbonate and hydrate co-gencrated.

The pigment formed by my process would most naturally be made by mixing solutions of barium oxid and zinc sulfate, but as barium oxid (or hydrate), is an article of relatively high cost, the price of a pigment so roduced would restrict 1ts use in commerce.

y my process I am able to take barium chlorid or other soluble salt of barium for the production of my pigment, and barium chlorid especially is an article procurable in commerce in a state of purity and cheapness and in abundance.

In carrying-out my process in the preferred way,. I proceed as follows: For each 1000 parts by weight of pigment to be produced,

take 914 arts by weight of zinc sulfate (ZnSO ,7 I-I 8 or its equivalent and dissolve in water. I then take 178 parts by weight of ure oxid of calcium or its equivalent, and mix to a smooth milk with" water. I

then mix thetwo solutions or mixtures thoroughly, and complete the reaction,- if necessary, by means of heat. I leave the mixture for some time, to complete the reaction,

or insure its completeness, whereby I have co-precipitated zinc oxid and calcium sulfate, according to the equation:

CilaHgOg 2110,11 0 (Iii-S0 2Aq Aq This sulfate of calcium has thenthe formula CaSO ,2H O, which has a molecular volume having practically the same ratio to that of barlum'sulfate as the ratio of volumes of the respective metals. This being the case, on now adding to the co-preci'pitated mixture of zinc oxid and calcium sulfate, 776 parts by wei ht, of barium chlorid, the barium and caIcium exchange places.

Ba(11 ,2H O CaSO ,2H O Aq V aSO CaCl till O Aq.

and barium sulfate in mo ecular proportions and co-precipitated, is drained and dried.

Hav' thus fully described my invention, what I bIaim as new and vsish to secure by Letters P'atent of the United States, is

In a process for producing a composite pigment, the 'rocess of co-prccipitating zinc oxid and calcium sulfate by mutual reaction of zinc sulfate and calcium oxid, both in solution, and then acting on the co-prccipitated salts with barium chlorid in solution whereby barium sulfate is produced in a relation of c'o-precipitation to the zinc oxid.

In Witness whereof, I, have hereunto set my hand and seal at Indianapolis, Indiana, this 31st day of December, A. D. one thousand nine hundred and seven.

ANSIL MOFFATT. 

